Abstract

The authors describe the characteristics and application of a AlGaN light-emitting diode(LED) operated at repetition rate, pulse duration, average power, peak power, and bandwidth. The LED enables the fluorescence decay of weakly emitting phenylalanine to be measured routinely, even in dilute solution. For of 6–9.2, the authors find evidence for a biexponential rather than monoexponential decay, providing direct evidence for the presence of phenylalanine rotamers with a photophysics closer to the other two fluorescent amino acids tryrosine and tryptophan than has previously been reported.

Received 14 May 2006Accepted 28 June 2006Published online 10 August 2006

Acknowledgments:

One of the authors (D.J.S.B.) wishes to thank the Wolfson Foundation, the Wellcome Trust, and EPSRC for research grants. Two of the authors (C.D.M. and A.M.M.) acknowledge the support of EPSRC research studentships. The technical assistance provided by John Broadfoot, John Revie, and Paul Thompson is gratefully acknowledged.